Japanese patent publication No. 9-250964 A discloses a fluid pressure sensor package with a sensor chip formed from a semiconductor substrate such as a silicon substrate. The sensor chip is designed to include a diaphragm and a sensing element which converts a mechanical stress into an electric signal. The sensor chip is accommodated within a casing with its diaphragm exposed to a fluid introduced through a probe tube integrally extending from the casing. The probe tube has a fluid channel for introducing the fluid into contact with the diaphragm. The fluid channel is designed to have a length and a diameter specific to a target fluid as well as a practical application environment. Since the probe tube is molded integrally with the casing, various sensor packages having differently shaped probe tubes have to be prepared for different application environments.